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Re: Everyone with high mileage vehicles.....

My understanding of it is that brake fluid is hygroscopic (that is, takes on water readily). In theory, that could mean water contamination over time, but if I'm being honest, I've never done a full brake line purge, even when my truck was creeping up on 150,000 miles, which was just before I traded it in.

Re: Everyone with high mileage vehicles.....

Before they (manufacturers) tightened up on parts tolerances, brake cylinders used to leak enough that brake fluid got replaced by necessity over time.

Concerning the difference between man and the jackass: some observers hold that there isn't any. But this wrongs the jackass.Mark Twain - Notebook, 1898
Clothes make the man. Naked people have little or no influence in society. --Mark Twain

Re: Everyone with high mileage vehicles.....

Originally Posted by Rocketman

If it looks like water or piss, its good. Don't waste your money. I've never seen brake lines rust from the inside.

It is not about rust, it is about safety.

In theory, water will find its way to the lowest pont in the system, since brake fluid floats on water, meaning brake fluid with water in it might have water near the caliper where it gets hot. Hot boiling water is a gas and can compress, leading to spongy poorly performing brakes under a load.

Modern systems are pretty good about keeping the water out, but getting rid of old fluid isn't a bad idea.

D

"A patriot is mocked, scorned and hated; yet when his cause succeeds, all men will join him, for then it costs nothing to be a patriot." Mark Twain
Alcohol, Tobacco, Firearms and Explosives.... now who's bringing the hot wings?

Re: Everyone with high mileage vehicles.....

Nowadays you can get gluten-free brake fluid, some brands are artificially sweetened and 0 calories - no sugar or high fructose corn syrup. The fluid squeezed from the pulp of the GMO brake fluid plant is the best - cheaper than the organic, and lasts lots longer.

Re: Everyone with high mileage vehicles.....

Originally Posted by BigDanS

It is not about rust, it is about safety.

In theory, water will find its way to the lowest pont in the system, since brake fluid floats on water, meaning brake fluid with water in it might have water near the caliper where it gets hot. Hot boiling water is a gas and can compress, leading to spongy poorly performing brakes under a load.

Modern systems are pretty good about keeping the water out, but getting rid of old fluid isn't a bad idea.

D

Dan is spot on with the theory of replacing brake fluid. I live in disgustingly flat terrain where nobody in there right mind could get brakes that hot. But I'd like to hear from guys that live where 10 miles of 6-7% grades are found. Using only the brakes without a lower transmission gear going down could get the brakes hot enough to get spongy.

Denny

Participating in a gun buy back program because you think that criminals have too many guns is like having yourself castrated because you think your neighbors have too many kids.... Clint Eastwood

Re: Everyone with high mileage vehicles.....

There is one very legitimate reason to change brake fluid that hasn't been mentioned- - - - -anti-lock brakes. During normal brake operation the same few ounces of fluid keeps getting cycled in and out of the wheel cylinders and calipers. No problem so far, except that small amount of fluid is constantly exposed to the thermal cycling of repeated brake applications. It gets cooked on a regular basis, whether or not it's apparent. All that energy that gets consumed by burning thousands of gallons of gasoline over 100K miles to get the car moving has to be dissipated somehow to make the thing stop- - - - - -hello, brakes!

Now let's throw in a panic stop or three which causes all that contaminated fluid to get cycled through a VERY expensive set of solenoid valves while the computer modulates the brakes to keep the car stopping in a relatively straight line, while the driver's bunghole sucks up a couple of inches of upholstery. Now there's all sorts of nasty gunk clogging up solenoid valves with tolerances somewhere in the neighborhood of a strand of hair cut into 10 equal slices. Want to take any bets on whether or not the ABS system is going to work right the next time you need it? A few ounces of fresh brake fluid is pretty cheap life insurance, IMHO!
Jerry

Last edited by Teach; 03-20-2017 at 11:43 PM.

Hide and wail in terror, Eloi- - - -We Morlocks are on the hunt!Just an old fart making the PC Patrol earn their pay!

Re: Everyone with high mileage vehicles.....

Originally Posted by Teach

There is one very legitimate reason to change brake fluid that hasn't been mentioned- - - - -anti-lock brakes. During normal brake operation the same few ounces of fluid keeps getting cycled in and out of the wheel cylinders and calipers. No problem so far, except that small amount of fluid is constantly exposed to the thermal cycling of repeated brake applications. It gets cooked on a regular basis, whether or not it's apparent. All that energy that gets consumed by burning thousands of gallons of gasoline over 100K miles to get the car moving has to be dissipated somehow to make the thing stop- - - - - -hello, brakes!

Now let's throw in a panic stop or three which causes all that contaminated fluid to get cycled through a VERY expensive set of solenoid valves while the computer modulates the brakes to keep the car stopping in a relatively straight line, while the driver's bunghole sucks up a couple of inches of upholstery. Now there's all sorts of nasty gunk clogging up solenoid valves with tolerances somewhere in the neighborhood of a strand of hair cut into 10 equal slices. Want to take any bets on whether or not the ABS system is going to work right the next time you need it? A few ounces of fresh brake fluid is pretty cheap life insurance, IMHO!
Jerry

So... how often?

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Re: Everyone with high mileage vehicles.....

I drive about 175 miles /day in Charleston SC- Ford F150, lots of times towing a trailer, gas to the floor then brake to the floor is the only way to get anywhere in a reasonable amount of time, I normally drive my trucks at least 250k miles, it was suggested to me to flush the brake fluid on my truck at 150k miles and it improved my brake pedal feel and stopping power so much it is now part of my standard hi mileage routine( 6 trucks). It has made a noticeable difference on all my trucks, Fords, Dodges and Toyotas both 150/1500 sized and 250/2500 sized

Re: Everyone with high mileage vehicles.....

Originally Posted by Teach

There is one very legitimate reason to change brake fluid that hasn't been mentioned- - - - -anti-lock brakes. During normal brake operation the same few ounces of fluid keeps getting cycled in and out of the wheel cylinders and calipers. No problem so far, except that small amount of fluid is constantly exposed to the thermal cycling of repeated brake applications. It gets cooked on a regular basis, whether or not it's apparent. All that energy that gets consumed by burning thousands of gallons of gasoline over 100K miles to get the car moving has to be dissipated somehow to make the thing stop- - - - - -hello, brakes!

Now let's throw in a panic stop or three which causes all that contaminated fluid to get cycled through a VERY expensive set of solenoid valves while the computer modulates the brakes to keep the car stopping in a relatively straight line, while the driver's bunghole sucks up a couple of inches of upholstery. Now there's all sorts of nasty gunk clogging up solenoid valves with tolerances somewhere in the neighborhood of a strand of hair cut into 10 equal slices. Want to take any bets on whether or not the ABS system is going to work right the next time you need it? A few ounces of fresh brake fluid is pretty cheap life insurance, IMHO!
Jerry

This is why I usually flush my fluid every few years or when the system is opened. Fresh fluid definitely improves pedal feel and gives me peace of mind. After 3 years, roughly 3-4 ft up the lines is pretty dark and burnt smelling. With the right tools, it doesn't take too much longer than an oil change.

Re: Everyone with high mileage vehicles.....

Originally Posted by Teach

There is one very legitimate reason to change brake fluid that hasn't been mentioned- - - - -anti-lock brakes. During normal brake operation the same few ounces of fluid keeps getting cycled in and out of the wheel cylinders and calipers. No problem so far, except that small amount of fluid is constantly exposed to the thermal cycling of repeated brake applications. It gets cooked on a regular basis, whether or not it's apparent. All that energy that gets consumed by burning thousands of gallons of gasoline over 100K miles to get the car moving has to be dissipated somehow to make the thing stop- - - - - -hello, brakes!

Now let's throw in a panic stop or three which causes all that contaminated fluid to get cycled through a VERY expensive set of solenoid valves while the computer modulates the brakes to keep the car stopping in a relatively straight line, while the driver's bunghole sucks up a couple of inches of upholstery. Now there's all sorts of nasty gunk clogging up solenoid valves with tolerances somewhere in the neighborhood of a strand of hair cut into 10 equal slices. Want to take any bets on whether or not the ABS system is going to work right the next time you need it? A few ounces of fresh brake fluid is pretty cheap life insurance, IMHO!
Jerry

My work truck is a 99 Dodge. It had an intermittent problem with pulling to the left under hard braking. Turns out it was the ABS control module and valves had gotten junked up. That's about 2 grand to fix... OTOH, flushing the brake fluid every so often.... much cheaper.

Re: Everyone with high mileage vehicles.....

This is the best explanation I have seen yet. Still think don't think it's necessary. When was the last time you activated the ABS on your car? I haven't used ABS in 14 years.

How do you know this? Does your car send you an email? If you ever drive in the rain and have someone cut in front of you or had some other occurrence cause you to brake aggressively, you have likely activated your ABS.

Re: Everyone with high mileage vehicles.....

Originally Posted by Fisheadgib

How do you know this? Does your car send you an email? If you ever drive in the rain and have someone cut in front of you or had some other occurrence cause you to brake aggressively, you have likely activated your ABS.

You will know it when the ABS activates. The pulses of releasing and applying the brakes is quite noticeable. My daughter came over one day and told me her truck was shaking when she applied the brakes. I asked her what happened and she said she almost rear ended someone and was standing on the brake hard. The shaking was the ABS doing what it does.

Re: Everyone with high mileage vehicles.....

Here's a simple trick that I taught every student who was willing to listen and had more than two or three brain cells that weren't fried by weed or harder drugs- - - - - -every time you change a set of brake pads it's necessary to push the pistons back into the caliper to make room for the new, thick brake pads you're installing. Instead of pushing that nasty-azz fluid that's been in the caliper for months or years back through all those sensitive solenoid valves and back into the master cylinder to contaminate the whole system, just crack the bleeder screw and let the grungy fluid spill out on the floor. Close the bleeder. Reassemble the brakes, top off the master cylinder, and pump the pedal a few times. You just put new, fresh fluid through the most sensitive part of the system, and refilled the calipers with fluid that might not be new, but it's clean. Top off the master cylinder a second time, and you're good to go until the next brake job.
Jerry

Hide and wail in terror, Eloi- - - -We Morlocks are on the hunt!Just an old fart making the PC Patrol earn their pay!

Re: Everyone with high mileage vehicles.....

Originally Posted by Buford

You will know it when the ABS activates. The pulses of releasing and applying the brakes is quite noticeable. My daughter came over one day and told me her truck was shaking when she applied the brakes. I asked her what happened and she said she almost rear ended someone and was standing on the brake hard. The shaking was the ABS doing what it does.

Had to stop in a hurry to keep from plowing into some nimrod the turned left in front of me. The brakes did their job and the nimrod went about her business unharmed. I definitely felt the ABS working.

Diplomacy is the art of saying 'Nice doggie' until you can find a rock.